The present invention relates to a two dimensional drive system.
An X-Y table, which is an example of conventional two-dimensional drive system, comprises: a base; an X-driving unit being arranged in an X-direction, fixed to the base, and capable of moving an X-moving body, in the X-direction, by an X-driving means; a Y-driving unit being arranged in a Y-direction, fixed to the X-moving body, moved together with the X-moving body in the X-direction, and capable of moving a Y-moving body, in a Y-direction, by a Y-driving means; and a top table being fixed on the Y-moving body.
In the conventional X-Y table, the top table, which is fixed to the Y-moving body, is directly moved, in the Y-direction, by the Y-driving means; the top table is indirectly moved, in the X-direction, by moving the Y-driving unit by the X-driving means.
A first point of the X-driving means, at which driving force of the X-driving means, which moves the Y-driving unit in the X-direction, is generated, and a second point, to which the driving force thereof works so as to move the Y-driving unit in the X-direction, in the top table, are separated. By the distance between the first and second points, moment is generated in the system and it badly influences positioning accuracy, resolution, inertia reductively and high speed operation ability.
In the conventional X-Y table, the Y-driving unit is piled on the X-driving unit, further the top table is piled on the Y-driving unit. With this structure, the weight of the top table fully works to the Y-driving unit, so that the Y-driving unit is bent and the positioning accuracy, etc. are made lower.
The inventor of the present invention invented a two dimensional drive system, and it was disclosed in Japanese Patent Gazette No. 5-92376, in which a moving body (slider) is moved in a first (X) direction and a second (Y) direction, which is perpendicular to the first (X) direction, by two ball screws.
The conventional two-dimensional drive system is shown in FIG. 10. The system comprises: a base 110; a pair of X-guides 114a and 114b being fixed to the base 110 and arranged in the X-direction; a pair of Y-guides 126a and 126b being fixed to the base 110 and arranged in the Y-direction; a pair of X-travelers 116a and 116b being capable of moving, in the X-direction, along the X-guides 114a and 114b; a pair of Y-travelers 128a and 128b being capable of moving, in the Y-direction, along the Y-guides 126a and 126b; an X-ball screw 134 being arranged in the X-direction and spinably spanned between the Y-travelers 128a and 128b; a Y-ball screw 138 being arranged in the Y-direction and spinnably spanned between the X-travelers 116a and 116b; a slider 142 being screwed with the X- and Y-ball screws 134 and 138 and capable of moving in the X- and Y-directions when the X-and Y-ball screws 134 and 138 spin; an X-servo motor 136 for spinning the X-ball screw 134; a Y-servo motor 140 for spinning the Y-ball screw 138; a pair of X-racks 112a and 112b being arrange, in the X-direction, alongside the X-guides 114a and 114b; a pair of Y-racks 124a and 124b being arrange, in the Y-direction, along side the Y-guides 126a and 126b; an X-rod 132 being rotatably arranged in the X-direction and capable of moving, in the Y-direction, with the movement of the Y-travellers 128a and 128b; a Y-rod 120 being rotatably arranged in the Y-direction and capable of moving, in the X-direction, with the movement of the X-travellers 116a and 116b; a pair of X-pinion gears 133a and 133b being coaxially fixed to the X-rod 132, respectively engaged with the Y-racks 124a and 124b and capable of rolling, in the Y-direction, with the movement of the X-rod 132; and a pair of Y-pinion gears 122a and 122b being coaxially fixed to the Y-rod 120, respectively engaged with the X-racks 112a and 112b and capable of rolling, in the X-direction, with the movement of the Y-rod 120.
In the two dimensional drive system, the slider 142, which corresponds to the top table of the X-Y table, can be directly moved, in the X- and Y-directions, by the X- and Y-ball screws 134 and 138. Namely, the first point and the second point are met and the slider 142 can be directly driven by the ball screws 134 and 138, so that the resolution of the ball screws 134 and 138 can be directly mirrored to the resolution of the slider 142. Namely, the positioning accuracy, etc. of the slider 142 can be improved.
The slider 142 is supported by not only the guides 114a, 114b, 126a and 126b but also an X-slider guide 130 and a Y-slider guide 118. With this structure, deformation of the beam-shaped slider guides 130 and 118 can be limited, so that the positioning accuracy, etc. can be improved.
Further, the slider 142 can be moved in a hollow space, an operator can efficiently work in the hollow space.
However, in the case of using the two-dimensional drive system as an X-Y table, the slider guides 118 and 130 are bent and a level of the slider 142 is made lower, if a heavy thing is mounted onto the slider 142. If the level of the slider 142 is made lower, the positioning accuracy, etc. of the drive system is made lower.
On the other hand, in the conventional X-Y table, the X-driving unit is fixed to the base, and manufacturing accuracy of a surface of the base influences to the positioning accuracy of the top table. Thus, the positioning accuracy of the X-Y table cannot be improved without improving the manufacturing accuracy of the surface of the base.